Oil-burning fire box



Nov; 1, 1938. w, B GRAHAM OIL BURNING FIRE- BOX Filed Feb. 24, 1936 Wade B. Graham ATTORNEYfi Patented Nov. 1, 1938 UNITED STATES PATENT OFFICE 2 Claims.

This invention relates to oil burning locomotives and to mechanism embodying steam generating units of similar construction, and is particularly concerned with an improved fire box construction.

In the construction of oil burning locomotives, it is conventional to equip the -fire boxes with draft bottoms formed with a single opening located adjacent the wall opposite the fuel nozzle. This opening is made of a size to permit the entrance of a sufiicient amount of air to effect efiicient combustion when the throttle is open and a forced draft maintained by the steam exhausted from the engine cylinders, and is so positioned that it effects the proper distribution of the air under such conditions. Such opening does not, however, permit the entrance of a sufficient amount of air to effect efiicient combustion, or act to properly distribute the air when the throttle is closed or but slightly open and a much smaller draft maintained by a steam blower. The inefiicient combustion resulting under the latter conditions causes the formation of carbon on the draft bottom, the emission of gas into the engine cab, the production of internal explosions resulting in flashes of fire being expelled into the cab through the fire door, and the loosening of the brick in the fire box.

It is an object of this invention to provide a fire box construction which will result in the elimination of the above named objectionable features in locomotives, and which may be employed in mechanisms embodying similar steam generating units to effect a like result.

The invention will be best understood from the description of one practical embodiment thereof, illustrated in the accompanying drawing, in which:

Fig. 1 is a perspective view of a draft bottom for a fire box of the type contemplated by this invention.

Fig. 2 is an enlarged fragmentary section of the member illustrated in Fig. 1 taken through one of the upwardly extending tubes; and

Fig. 3 is a longitudinal sectional view of the lower portion of a fire box embodying the present invention, the rear lower portion of the boiler being illustrated in dot and dash lines.

The fire box illustrated in the drawing is designed for use in a conventional locomotive of the type in which the fire box is located at the rear of the boiler and communicates with the smokestack through the fiues of the boiler.

Referring to Fig. 3, the letter A indicates the rear bottom portion of the boiler of a locomotive;

the letter B the lower portion of the fire box of the locomotive commonly called a fire pan. The fire pan B comprises a sheet metal shell consisting of a rectangular structure It and of a plate I I supported in the bottom of the structure 10 by means of flanges l2. The plate II, which constitutes the draft bottom of the fire box, is con structed with a large opening l3 adjacent the rear Wall of the fire box and with a plurality of smaller openings I l arranged between the large opening i3 and the forward end of the box. The large opening [3 is surrounded by an upwardly extending metal structure I5 consisting of a plurality of suitably shaped angle irons, and mounted in each of the apertures M there is an upstanding tube 16. The fire box is lined with firebricks ll, except for that portion of the bottom which is occupied by the tubes [6. This portion of the bottom is lined with a layer of fire-proof cement [3 which fills the spaces between the tubes [6.

At the forward end of the fire box, there is a flooring C which closes the opening between the fire box and the adjacent wall of the boiler. This flooring comprises a sheet metal plate [9 supported in place by angle members 20 and covered with firebrick ll.

The forward wall of the sheet metal structure II] is formed with an aperture 2! and the bricks at that end of the fire box separated so as to provide an opening into the interior of the fire box for a fuel injection nozzle 22. The nozzle 22 is of a steam actuated injection type, and is fed with oil from a pipe line 23 and with steam from a pipe line 24. The flow of steam and oil through the pipe lines 23 and 24 is controlled in the usual manner by means of manually operated valves located in the engine cab.

During the operation of the engine, fuel is injected into the fire box B in the direction of the rear wall which, in the parlance of the art, is called, a flash wall in that it is maintained at a white heat capable of igniting the fuel. The injected fuel burns within the fire box, air being supplied by way of the opening l3 and the tubes it. The gases of combustion pass upwardly and forwardly into the boiler flues and from there into the forward compartment of the engine where they are expelled through the smoke-stack.

During the periods when the engine throttle is open, a forced draft is maintained through the fire box as a result of the steam exhausted from the engine cylinders being expelled through the smoke-stack. This forced draft is eliminated when the throttle is closed, and is ineffective with a slight opening of the throttle. At such times, a

steam blower mechanism arranged to create an auxiliary forced draft is opened. The steam passing through the blower mechanism produces a much smaller depression at the forward end of the boiler flues than the exhaust steam when the throttle is open, and in locomotives in which the fire boxes are equipped with conventional draft bottoms having a single opening, inefiicient combustion results from insufficient air being drawn into the fire box and from improper distribution of the indrawn airv This insufiicient combustion results notwithstanding that the fuel supply is reduced, as is done when the throttle is maintained closed or in a nearly closed position for substantial periods of time, and causes the objectional features previously set forth, including the production of dangerous explosions. With a draft bottom of the type herein described, efficient combustion is maintained during periods in which the throttle is closed, both with a normal fuel supply and with a reduced fuel supply, notwithstanding that there is a lessened tendency to draw air into the fire box. This maintenance of eflicient combustion results from the draft bottom being formed with a large number of openings arranged to provide more equal distribution of the air entering the fire box, and from the mixing of the air with the fuel produced by the jets of air entering through the tubes l6.

What is claimed is:

1. A fire box for locomotives comprising a fire pan, said pan including front, rear and bottom Walls, fire brick on said front and rear walls, said bottom wall having a draft opening substantially across the end adjacent said rear wall, and also having a plurality of additional air inlets, each of said inlets being of less area than said opening and said inlets being distributed over said bottom wall, and a liquid fuel spray burner in said forward Wall to direct a spray of fuel along the fire box across said inlets and against said rear wall, said inlets serving to admix air with and assist in vaporizing the fuel before it reaches said rear wall.

2. A fire box of the character described comprising a box portion having front and rear walls and a substantially horizontal base, fire brick linings on said walls, said base having an elongated draft opening at one end thereof, a plurality of small upstanding air inlet tubes extending through and distributed over the base of said box to provide for distribution of air admitted to said box, said base including a body of refractory cement surrounding said tubes, and means to inject liquid fuel into said box across said air inlets and over said elongated draft opening.

WADE B. GRAHAM. 

